A research team led by scientists from Boise State University and NASA’s Goddard Space Flight Center has identified several complex cyanide compounds in a set of CM chondrite meteorites. These extraterrestrial organometallic compounds are a source of free cyanide and also bear a striking similarity to portions of the active sites of hydrogeneses (enzymes that provide energy to bacteria and archaea by breaking down hydrogen gas), which suggests that these compounds may have played an important role during the origin and early evolution of life on Earth.

“Cyanide, a carbon atom bound to a nitrogen atom, is thought to be
crucial for the origin of life, as it is involved in the non-biological
synthesis of organic compounds like amino acids and nucleobases, which
are the building blocks of proteins and nucleic acids used by all known
forms of life,” said Dr. Karen Smith, a researcher at Boise State
University.

Dr. Smith and colleagues developed new analytical methods to extract and measure ancient traces of cyanide in meteorites.

“One of the most interesting observations from our study is that
these iron cyano-carbonyl complexes resemble portions of the active
sites of hydrogenases, which have a very distinct structure,” said Dr.
Mike Callahan, from Boise State University and NASA’s Goddard Space
Flight Center.

Hydrogenases are present in almost all modern bacteria and archaea and are widely believed to be ancient in origin.

They are large proteins, but the active site — the region where
chemical reactions take place — happens to be a much smaller
metal-organic compound contained within the protein. It is this compound
that resembles cyanide compounds the team discovered in CM chondrites.

“Cyanide and carbon monoxide attached to a metal are unusual and rare in enzymes,” Dr. Smith said.

“Hydrogenases are the exception. When you compare the structure of
these iron cyano-carbonyl complexes in meteorites to these active sites
in hydrogenases, it makes you wonder if there was a link between the
two.”

“It’s possible that iron cyano-carbonyl complexes may have been a
precursor to these active sites and later incorporated into proteins
billions of years ago. These complexes probably acted as sources of
cyanide on early Earth as well.”

The research was described in a paper in the journal Nature Communications.